In a zero field Cu NQR (\(m\)  = \(\pm \) 3/2 \(\leftrightarrow \)  \(\pm \) 1/2),
the theoretical recovery curve with mixed magnetic and quadrupole relaxation is a single exponential function with a time constant \(T_1\)  [1]}.
The magnetic dipole transition probability with \(\Delta m\)  = \(\pm \) 1, the quadrupole transition probabilities with \(\Delta m\)  = \(\pm \) 1 and \(\pm \) 2 are additive in the single relaxation rate \(W_1\equiv \) 1/\(T_1\) .
Thus, the experimental relaxation rates \(^{\eta }W_1\)  are expressed by the sum of the nuclear magnetic relaxation rate \(^{\eta }W_M\)  and the nuclear quadrupole relaxation rate \(^{\eta }W_Q\)  as
\(^{63}W_1 &=& ^{63}W_M + ^{63}W_Q,\\^{65}W_1 &=& M_r ^{63}W_M + Q_r ^{63}W_Q,\) 
